Fragrance-emitting devices or articles such as air fresheners are known. Practically, such devices or articles must emit the fragrance at a controlled rate over a prolonged period of time. Moreover, it is particularly desirable that the device or article is designed in order that the fragrance is not emitted to the atmosphere until wanted or needed. This is usually accomplished by enclosing the fragrance-emitting article in a vapor-impermeable package, with the package being opened, exposing the fragrance-emitting article or device to the atmosphere when the article or device is placed in use. This requires, therefore, that the fragrance emitted from the article or device reach an equilibrium within the enclosed package permitting prolonged storage of the device while enclosed, with activation occurring only when the package is opened.
Foams including polyurethane foams, because of their low cost and ready availability, have been suggested for use as or in fragrance-emitting articles or devices. It has been generally recognized, however, that while perfumes or fragrance bearing foams can be made by impregnating pre-made foams with a fragrance-emitting material, such foams have only short life before the fragrance is exhausted from a use standpoint. Additionally, large amounts of the fragrance material is lost in the preparation of the perfumed foam. It has also been proposed that a fragrance material be incorporated into a polyurethane foam during the foam-forming process. It has been found, however, that the fragrance material being a high volatile or relatively high volatile substance is volatilized during the formation of the foam due to the highly exothermic reaction which occurs during foaming. Therefore, not enough fragrance remains in the foam for practical application. Additionally, the evolution of the fragrance material during foaming can detrimentally affect the physical characteristics of the foam.
It has also been proposed in U.S. Pat. No. 4,226,944 that foams can be made by mixing the fragrance material with a dry particulate filler, adding this premix to a liquid polyol to form a second mixture, and then introducing the second mixture into a reaction zone together with an organic di- or polyisocyanate, a blowing agent, and a catalyst to produce a polyurethane foam-forming reaction mixture. The dry particulate material as disclosed in the patent can be clay, limestone, soap, detergent, or mixtures thereof. These particulate materials have a pre-existing structure, possibly porous, and, accordingly, the liquid fragrance material will either be adsorbed or absorbed to the surface of the particles or into the pores of the particles if porous. While foams produced according to the patent allegedly will emit the fragrance over a protracted period of time at ambient conditions and since the fragrance material is premixed with the dry particulate filler at the time of the foaming with the fragrance material being thereby adsorbed or absorbed by the filler, there still will be a substantial loss of the volatile perfume during the foaming operation. Again the evolution of the volatile substance can detrimentally affect the physical characteristics of the foam, including uniform cell size, freedom from pinholing, good structural stability, and strength.